This invention relates to converting analog values to digital integers.
Conversion of an analog signal to an equivalent digital representation is conventionally required for subsequent digital processing of that signal. Two important portions of the conversion process consist of quantizing the analog signal into one of a series of discrete values and then uniquely coding that value. For example, digital signal processing (DSP) of a radar signal by a digital computer requires that the analog radar signal first be converted to a corresponding digital code, or format, that is compatible with and understood by the digital computer. The choice of a particular digital format, e.g., binary format, is dictated by the DSP computer's architecture and the processing algorithms implemented on the computer.
One possible digital format for representing an analog signal in a DSP computer is the digital residue number format. Using this format, the value of an analog signal may be represented by one or more digitized integer "residues", or remainders, with each residue corresponding to a particular residue base, or divider. Given this equivalent digital representation by a set of residues, the value of an analog signal is effectively decomposed into component factors which may be digitally processed independently and in parallel.
The digital residue format is particularly well suited for high-speed DSP operations on an analog signal; a conventional DSP computer can complete a set of simultaneous, parallel component operations much faster than it can complete the equivalent single serial operation. In particular, if the DSP parallel component-operations each require a smaller computer word size than the equivalent serial operation, and can proceed independently of the other component-operations, the overall efficiency of a DSP mathematical computation may be significantly increased using component-operations. Furthermore, DSP algorithms which require many repetitive operations, such as fast Fourier transforms, may be implemented with elementary, rather than complex, hardware if the repetitive operations are decomposed into elementary sub-operations. Thus, the digital residue representation of an analog signal provides an ideal format for fast, efficient DSP processing of that signal.
Conventionally, an analog signal is indirectly converted to a digital residue representation by first converting the analog signal to a binary format that represents the decimal value of the signal, and then digitally processing that format to achieve another binary format that represents the desired digital residue value of the signal.